With smartphones and tablets quickly gaining widespread adoption, even IBM is calling this a “post-PC era”. It’s a world of portability, apps, and touch-enabled devices. This is clear not only in the dominance of mobile devices and laptops on the hardware side, but in the way that Apple and Microsoft are merging their mobile and desktop operating systems.

Apple began incorporating iOS features into OSX with its Lion release in mid-2011, and will continue adding them with Mountain Lion, announced today and due by the end of the summer. Microsoft used its Windows Phone 7 for inspiration, and will release its Windows 8 beta for both desktops and tablets--rumored for the end of February--and possibly a phone based on Windows 8 later in the year. The two approaches appear to yield similar results.

Here are seven ways both Mountain Lion and Windows 8 include features that were initially found on mobile devices:

Apple popularized the App Store with iOS, and in Lion added a Mac App Store so that OSX users could purchase apps and even operating system upgrades online. Mountain Lion will give preference to “safer” App Store apps, and even provide an option to prevent installation of non-App Store apps. Windows 8 will include the Windows Store with similar functionality, meant to allow easy browsing, purchasing and installation of Windows apps.

2. Full Screen

The Windows 8 Metro interface will do away with the task bar and start menu in favor of full-screen apps, providing a tablet-like experience. Lion already introduced this option, and apps are increasingly supporting it as they are updated.

3. Cloud Sync

Syncing with the cloud is common for mobile devices, both as a backup option and to provide extended storage for devices that have a limited amount of local storage. Windows 8 will include integration with its SkyDrive cloud storage service, enabling users to sync Office documents, photos, and possibly more. Mountain Lion will expand Apple’s integration of iCloud to not only sync most apps, settings, and purchased media across your Apple devices, but also will behave like a disk in the cloud for documents.

4. Shared Apps

Microsoft will have apps available in its store that will run on both Windows 8 desktops and tablets. Some will even work on ARM-powered hardware. Apple’s Mountain Lion will include desktop versions of a number of its mobile apps, including Reminders, Notes, and Game Center, and it will rename the iChat desktop app to Messages to match its iOS counterpart.

5. Touch-Enabled

Windows 8's MetroThe Metro interface in Windows 8 was designed with touch-enabled devices in mind. Microsoft is also promising a touch-friendly version of its Office Suite. Apple has increasingly added multi-touch support and gestures to many of its apps, though they are all currently accomplished through built-in or add-on touchpads.

6. Resume and Standby

The Lion OS introduced Resume, allowing a PC to wake up quickly from sleep mode or even to restart, with all apps and documents restored to their previous state--much like how a smartphone or tablet resume earlier activities after not being used for some time. Windows 8 will include standby mode, enabling apps to better handle sleep interruptions, and it will even allow some network connectivity while sleeping, similar to the way phones receive updates while in your pocket.

Apple's LaunchPad7. LaunchPad and Widgets

Apple added LaunchPad in its Lion release, which displays apps in much the same way as iOS does, with multiple pages of icons organized in a grid. Windows 8 will use tile icons that act as shortcuts to apps, but also present information, much like widgets common on mobile devices do.